When Germany began launching the Fieseler Fi-103 V-1 at England from sites in France in 1944, the U.S. Army had been interested in starting a missile program. An unexploded Fi-103 was shipped to America for study. In September 1944 the Republic company was awarded the contract to build duplicates of the Fi-103, with the Ford Motor Co making the engine which was a copy of the Argus 014 Pulsejet, now known as the PJ-31-1.

In exactly two months the first operational JB-2's (Jet Bomb Model 2) came off the assembly line. After intensive testing the USAAF ordered 75,000 "Loons", how ever by the time the Second World War had ended there was no need for such a weapon in the numbers ordered (as there would be no invasion of Japan), so the contract was terminated after only 1200 JB-2's were built. The JB-2 was the first U.S. guided missile and it was intended to be launched from the ground, aircraft and ships, tests continued up to 1947 with the US Navy launching the JB-2 from submarines.

SPECIFICATIONS
Span: 17 ft. 8 in.
Length: 27 ft. 1 in.
Height: 4 ft. 8 in.
Weight: 5,023 lbs. loaded
Armament: 2,100 lb. high-explosive warhead
Engine: Ford PJ-31-F-1 of 900 lbs. thrust (copy of German Argus-Schmidt pulse-jet)

JB-2 Loon (Thunderbug)S/N 14305